Defense Secretary James Mattis ​accused​ Russian President Vladimir Putin of making ​international ​”mischief” and reassured allies that the US commitment to NATO is resolute, according to a report on Wednesday.

Saying Russia is challenging the “secure and peaceful” post-war order, Mattis said Putin​’s ​”making mischief beyond Russian borders will not restore their fortunes or rekindle their hope,” apparently referring to the Kremlin’s meddling in the 2016 presidential election and its involvement in Ukraine, Agence France-Presse reported on Wednesday.

Mattis, a former four-star Marine Corps general, made the comments during an address to German students on the 70th anniversary of the Marshall Plan that rebuilt Europe after World War II. It was his fourth trip to Germany since becoming defense secretary.

He also said the US’ commitment to Article 5 of the NATO alliance, which says an attack on one member is an attack on all members, is “iron-clad.”

​Mattis highlighted President Trump’s request for an increase in the ​​European Reassurance Initiative​, a program to improve the readiness of forces in Europe,​ to $4.8 billion this year from $3.4 billion last year.

“Beyond any words in the newspapers, you can judge America by such actions,” Mattis said.